R 使用ggplot打印比例而不是计数

我试图将两个因素（即计数）w.r.t与一个连续变量上的组合的比例可视化。下面是一个小的运行示例

df <- data.frame(s=as.factor(c("0","1","1","0","1","0","0")),
                 density=c(1.1,1.3,1.4,2.1,2.3,2.2,2.4),
                 n=as.factor(c("A","A","A","A","A","A","A")))

ggplot(df, aes(x = density, fill = s)) + 
  geom_histogram(position = "stack", bins = 2) + 
  facet_wrap("n", scales = "free")

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df stat参数实际上有一个选项“fill”。。。这就是你要找的吗？