如何在 Ggplot 中让每个方面都具有不同的颜色

如何解决如何在 Ggplot 中让每个方面都具有不同的颜色

以下是示例数据、操作和 ggplot 代码。我的问题是我将如何为这些方面或项目中的每一个指定背景颜色？我知道如何将它们全部变成一种颜色或其他颜色，但我正在摸索如何将它们变成三种不同的颜色？

#Data generation
Month1 <- c(201811,201812,20191,20192,20193,20194,20195,20196,20197,20198,20199,201910,201911,201912,20201,20202,20203,20204,20205,20206,20207,20208,20209,202010,202011)
Rate <- 
c(3.2,3.3,3.4,3.1,3.0,2.9,2.6,2.5,2.3,2.1,1.6,1.7,1.5,1.1,-0.4,-19.5,-17.6,-10.5,-9.6,-9.1,-8.6,-8.0,-7.7)

 cesyoym <- data.frame(Month1,Rate)

#Chart
library(ggplot2)
library(dplyr)
library(lubridate)
library(scales)
library(odbc)

 ##date

 

 linechartm<-cesyoym %>% 
 mutate(year = substr(as.character(Month1),1,4),month = substr(as.character(Month1),5,7),date = as.Date(paste(year,month,"1",sep ="-"))) %>%  
 ggplot() + 
 geom_line(aes(x = date,y = Rate)) +
 geom_rect(xmin = -Inf,ymin = -Inf,xmax = Inf,ymax = Inf,alpha = 0.1,aes(fill = year)) +
 facet_wrap(~year,scales = "free_x") +
 scale_y_continuous(labels = scales::percent) +
 scale_x_date(date_breaks="1 month",date_labels="%b\n") + 
 ggtitle("Employment  Growth (%)") +
 theme(panel.grid.major = element_blank(),axis.text.x = element_text(angle = 90,size = rel(0.6)),panel.spacing = unit(0,"lines"),strip.placement = 'outside',strip.background = element_blank()) +
 scale_fill_brewer(palette = "Spectral") + 
 guides(fill = FALSE)

print(linechartm)