Black Lives Matter. Please consider donating to Black Girls Code today.

Overlaying Line with stacked area chart

Is there a way to overlay a line chart to a stacked (and grouped) area chart? Something like below

library(plotly)
data <- t(USPersonalExpenditure)
data <- data.frame("year"=rownames(data), data)
data$test <- 200
fig <- plot_ly(data, x = ~year, y = ~Food.and.Tobacco, name = 'Food and Tobacco', type = 'scatter', mode = 'lines', stackgroup = 'one', fillcolor = '#F5FF8D')
fig <- fig %>% add_trace(y = ~Household.Operation, name = 'Household Operation', fillcolor = '#50CB86')
fig <- fig %>% add_trace(y = ~Medical.and.Health, name = 'Medical and Health', fillcolor = '#4C74C9')
fig <- fig %>% add_trace(y = ~Personal.Care, name = 'Personal Care', fillcolor = '#700961')
fig <- fig %>% add_trace(y = ~Private.Education, name = 'Private Education', fillcolor = '#312F44')
fig <- fig %>% layout(title = 'United States Personal Expenditures by Categories',
                      xaxis = list(title = "",
                                   showgrid = FALSE),
                      yaxis = list(title = "Expenditures (in billions of dollars)",
                                   showgrid = FALSE))
fig %>% 
  add_lines(x= data$year, y = 200)