Help with replicating forcats example from r4ds book

r4ds
tidyverse

#1

Not getting correct results for this example from r4ds book section on forcats. Tried to use this in class and got the following. Any ideas? Probably something simple i am doing wrong.
by_age <- gss_cat %>%
filter(!is.na(age)) %>%
group_by(age, marital) %>%
count() %>%
mutate(prop = n / sum(n))

ggplot(by_age, aes(age, prop, colour = marital)) +
geom_line(na.rm = TRUE)

by_age

A tibble: 351 x 4

Groups: age, marital [351]

 age       marital     n  prop


1 18 Never married 89 1
2 18 Married 2 1
3 19 Never married 234 1
4 19 Divorced 3 1
5 19 Widowed 1 1
6 19 Married 11 1
7 20 Never married 227 1
8 20 Separated 1 1
9 20 Divorced 2 1
10 20 Married 21 1

… with 341 more rows


#2

You could use

summarise(n = n())

instead of count. This will reduce the groups to “age”. And your plot will show something more informative.