R 将符号作为第三个变量添加到 ggplot 图中

我有一个堆积图，我已经有两个变量了.我想在图表中添加第三个变量作为符号或对象.这是我想要的图表:

我当前的代码是:

sur %>% 
  filter(!(species_broad %in% c("Monkey", "Cattle"))) %>%
  drop_na(circumstances_bite_broad_intended) %>%
  add_count(species_broad) %>%
  mutate(y_species_broad = 
           reorder(
             factor(paste0(species_broad, "\n", "(n = ", n, ")")),
             as.numeric(species_broad)
           )) %>% 
  ggplot(mapping=aes(y= y_species_broad, fill=circumstances_bite_broad_intended)) + 
  geom_bar(colour="black" , position = "fill")+
  scale_x_continuous (labels=c("0","25%","50%","75%","100%"))  +
  labs (x="Proportion of responses",y="Animal species" , fill="Circumstances")+  # "fill" to change the legend title 
  ggtitle ("Circumstances of bite in different animal species")+ 
  scale_fill_manual( values =c ("Threatening Engagement" = "darkred" ,
                                "Friendly Engagement" = "red" , 
                                "Practical Engagement" = "#EC7979" ,
                                "Unintentional Human Engagement" = "lightblue" ,
                                "Apparently unprovoked" = "darkblue"))

我的数据是:

structure(list(species = structure(c(1L, 1L, 3L, 5L, 1L, 2L, 
7L, 2L, 2L, 1L, 3L, 1L, 2L, 3L, 1L, 2L, 1L, 4L, 4L, 7L, 2L, 1L, 
2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 2L, 2L, 3L, 2L, 1L, 1L, 1L, 6L, 7L, 9L), levels = c("Pet dog", 
"Unowned dog", "Dog (unknown status)", "Pet cat", "Unowned cat", 
"Cat (unknown status)", "Rat/rodent", "Monkey", "Cattle"), class = "factor"), 
    circumstances_bite_avoidability = structure(c(1L, 2L, 1L, 
    1L, 2L, 2L, 2L, 2L, 2L, 1L, 2L, 1L, 2L, 2L, 2L, 1L, 2L, 2L, 
    1L, 2L, 2L, 1L, 2L, 1L, 1L, 2L, 2L, 1L, 1L, 2L, 1L, 2L, 1L, 
    1L, 2L, 2L, 2L, 2L, 2L, 1L, 2L, 2L, 1L, 1L, 2L, 2L, 1L, 1L, 
    2L, NA), levels = c("Avoidable", "Unavoidable"), class = "factor"), 
    circumstances_bite_broad_intended = structure(c(2L, 4L, 1L, 
    3L, 4L, 4L, 4L, 5L, 5L, 3L, 5L, 1L, 4L, 5L, 5L, 1L, 5L, 5L, 
    2L, 5L, 4L, 3L, 5L, 2L, 2L, 5L, 4L, 3L, 3L, 5L, 1L, 5L, 1L, 
    1L, 5L, 5L, 4L, 4L, 5L, 1L, 5L, 5L, 1L, 1L, 5L, 5L, 2L, 3L, 
    5L, NA), levels = c("Threatening Engagement", "Friendly Engagement", 
    "Practical Engagement", "Unintentional Human Engagement", 
    "Apparently unprovoked"), class = "factor")), row.names = c(NA, 
50L), class = "data.frame")