r - ggplot2 stacked area line charts producing odd lines and holes -

i have data set that's structured follows:

year    color   toyota  honda   ford 2011    blue    66      75      13 2011    red     75      91      62 2011    green   65      26      57 2012    blue    64      23      10 2012    red     84      8       62 2012    green   67      21      62 2013    blue    31      74      49 2013    red     48      43      35 2013    green   57      62      74 2014    blue    59     100      32 2014    red     72      47      67 2014    green   97      24      70 2015    blue    31       0      79 2015    red     60      35      74 2015    green   51       2      28 

(my actual data, presented in chart images below, larger , has 100s of "colors" i'm simplifying here can merely understand structure.)

i trying make stacked area line chart shows how many cars of each color produced on time specific company. (i.e. each company has own chart in x axis = years, y axis = cars produced).

i run code:

qplot(year, toyota, data = dataname, fill = color, group = color, geom= "area", position = "stack")  + geom_area() + theme(legend.position = "none") 

however, every company's chart has issues. there seemingly random cut-out holes lines cut across top of layers.

company1_chart

company2_chart

i'm confused why happening or possible (especially holes... won't data stack down?) if made companies long rather wide in data structure?

even 0 values, should not have errors. took data , added 0's in honda column sporadically.

the code (using ggplot2)

library(ggplot2) df <- read.csv("cartest.csv", header = true)  ggplot(data=df,aes(x=year,y=h,fill=color)) +    geom_area() +    ggtitle("car test") 

if importing data csv or tsv , data columns numeric should not have issue. if imported .character can convert using:

df$h <- as.numeric(df$h)