XSLT 1.0 Date Duration (Years) - xslt

Question

I'm using XSLT 1.0 to output the duration between two date fields. The following code (from https://stackoverflow.com/a/38615456/3016153) outputs the Duration in Days, Hours, Minutes, and Seconds as expected, but I need to update it to output Years as well. Does anyone have any suggestions on how I can update this code to output the Year duration? Alternative code is welcomed as well, but it must use XSLT 1.0
Any assistance is greatly appreciated.
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="event">
<xsl:variable name="start">
<xsl:call-template name="dateTime-to-seconds">
<xsl:with-param name="dateTime" select="start/#time" />
</xsl:call-template>
</xsl:variable>
<xsl:variable name="end">
<xsl:call-template name="dateTime-to-seconds">
<xsl:with-param name="dateTime" select="end/#time" />
</xsl:call-template>
</xsl:variable>
<xsl:variable name="duration" select="$end - $start" />
<xsl:variable name="d" select="floor($duration div 86400)"/>
<xsl:variable name="t" select="$duration mod 86400"/>
<xsl:variable name="h" select="floor($t div 3600)"/>
<xsl:variable name="r" select="$t mod 3600"/>
<xsl:variable name="m" select="floor($r div 60)"/>
<xsl:variable name="s" select="$r mod 60"/>
<xsl:copy>
<xsl:copy-of select="name"/>
<duration>
<xsl:value-of select="$d"/>
<xsl:text> days, </xsl:text>
<xsl:value-of select="$h"/>
<xsl:text> hours, </xsl:text>
<xsl:value-of select="$m"/>
<xsl:text> minutes and </xsl:text>
<xsl:value-of select="$s"/>
<xsl:text> seconds</xsl:text>
</duration>
</xsl:copy>
</xsl:template>
<xsl:template name="dateTime-to-seconds">
<xsl:param name="dateTime"/>
<xsl:variable name="date" select="substring-before($dateTime, 'T')" />
<xsl:variable name="time" select="substring-after($dateTime, 'T')" />
<xsl:variable name="local-time" select="substring($time, 1, string-length($time) - 6)" />
<xsl:variable name="offset" select="substring-after($time, $local-time)" />
<xsl:variable name="year" select="substring($date, 1, 4)" />
<xsl:variable name="month" select="substring($date, 6, 2)" />
<xsl:variable name="day" select="substring($date, 9, 2)" />
<xsl:variable name="hour" select="substring($local-time, 1, 2)" />
<xsl:variable name="minute" select="substring($local-time, 4, 2)" />
<xsl:variable name="second" select="substring($local-time, 7)" />
<xsl:variable name="offset-sign" select="1 - 2 * starts-with($offset, '-')" />
<xsl:variable name="offset-hour" select="substring($offset, 2, 2) * $offset-sign" />
<xsl:variable name="offset-minute" select="substring($offset, 5, 2) * $offset-sign" />
<xsl:variable name="a" select="floor((14 - $month) div 12)"/>
<xsl:variable name="y" select="$year + 4800 - $a"/>
<xsl:variable name="m" select="$month + 12*$a - 3"/>
<xsl:variable name="jd" select="$day + floor((153*$m + 2) div 5) + 365*$y + floor($y div 4) - floor($y div 100) + floor($y div 400) - 32045" />
<xsl:value-of select="86400*$jd + 3600*$hour + 60*$minute + $second - 3600*$offset-hour - 60*$offset-minute" />
</xsl:template>
</xsl:stylesheet>
Sample XML:
<events>
<event>
<name>Alpha</name>
<start time="2015-02-21T00:59:06+02:00"/>
<end time="2018-02-22T02:24:38+02:00"/>
</event>
<event>
<name>Bravo</name>
<start time="2016-02-21T00:59:06+02:00"/>
<end time="2020-03-05T02:24:38+02:00"/>
</event>
<event>
<name>Charlie</name>
<start time="2016-02-21T00:59:06+02:00"/>
<end time="2020-02-21T00:59:06+01:00"/>
</event>
enter code here

Answer 1

As stated in the comments, if you are willing to assume that every 365 days constitute a year, then all you need to do is change this part:
<duration>
<xsl:value-of select="$d"/>
<xsl:text> days, </xsl:text>
<xsl:value-of select="$h"/>
<xsl:text> hours, </xsl:text>
<xsl:value-of select="$m"/>
<xsl:text> minutes and </xsl:text>
<xsl:value-of select="$s"/>
<xsl:text> seconds</xsl:text>
</duration>
to:
<duration>
<xsl:value-of select="floor($d div 365)"/>
<xsl:text> years, </xsl:text>
<xsl:value-of select="$d mod 365"/>
<xsl:text> days, </xsl:text>
<xsl:value-of select="$h"/>
<xsl:text> hours, </xsl:text>
<xsl:value-of select="$m"/>
<xsl:text> minutes and </xsl:text>
<xsl:value-of select="$s"/>
<xsl:text> seconds</xsl:text>
</duration>
As also stated in the comments, it is rather rather strange that you would be willing to accept an error of approximately 1 day per 4 years in a calculation that calculates to seconds precision. If you only need precision of days, then you should save processor time and electricity by removing the parts that calculate the hours, minutes and seconds.