plot3 % + group_by(work_year, experience_level,avg_salary = mean(salary_in_usd, na.rm = TRUE))%>% + ggplot(mapping = aes(x=work_year, y =avg_salary, color = experience_level))+ + geom_line()+ + theme_bw()+ labs(x =

plot3 <- arshia %>% + group_by(work_year, experience_level,avg_salary = mean(salary_in_usd, na.rm = TRUE))%>% + ggplot(mapping = aes(x=work_year, y =avg_salary, color = experience_level))+ + geom_line()+ + theme_bw()+ labs(x = "Year",y = "Average salary (USD)", + title = "Average salary by experience level over time - 2020-2022")

plot3 + scale_color_manual(values = c("blue", "green", "red"))

Getting only one line instead of three lines