Manipulating {closest_state} in gganimate - regex

Question

I am relatively new to R and am attempting to use gganimate to plot the occurrences of a given phenomenon on a map of the United States. I have a column frameid which is calculated by multiplying a column week by 100 and adding the nth occurrence of said phenomenon. So the 7th occurrence of a phenomenon in New York in the first week of the dataset would have a frameid of 107, and the 7th occurrence of a phenomenon in Los Angeles would also have a frameid of 107. I am passing frameid into transition_states, but the problem is that I only want to display the week (i.e. everything but the last two characters, as the occurrences could never conceivably exceed 99), so I need to manipulate frameid somehow. The attempted solution:
labs(title = "My Title",
subtitle = paste("2019, Week",
substring("{closest_state}", 1, nchar("{closest_state}")-2)))
Returns 50 warnings, the first of which is "1: Cannot get dimensions of plot table. Plot region might not be fixed" and the last 49 of which are "Expecting '}'".
I have also tried:
gsub('.{3}$', '', "{closest_state}")
Which returns a similar error. Is there a solution or a workaround to this problem or can "{closest_state}" not be manipulated?
Here is the reproducible code:
library(ggplot2)
library(gganimate)
library(fiftystater)
sample <- data.frame(
frameid = c(101, 101, 101, 102, 102, 102, 201, 201, 201),
latitude = c(38.02262, 38.99691, 41.31194, 27.00071,
28.539, 30.2836, 38.02262, 38.03112,
40.21603),
longitude = c(-84.50521, -104.84369, -105.56906, -108.4121,
-81.4028, -97.73234, -84.50521, -78.51371,
-85.4177)
)
fortynine_states <- fifty_states %>%
filter(id != "alaska")
my_plot <- sample %>%
ggplot(aes(x = longitude, y = latitude)) +
geom_polygon(data = fortynine_states,
mapping = aes(long, lat, group = group),
fill = "white", color = "black") +
geom_point(aes(alpha = 0.2, color = "red")) +
coord_map() +
labs(title = "My Title",
subtitle = paste("2019, Week",
substring("{closest_state}", 1, nchar("{closest_state}")-2))) +
transition_states(frameid, transition_length = 2) +
exit_fade()
animate(my_plot, duration = 5, fps = 20, width = 400, height = 300, renderer = gifski_renderer())