fake time series data

# add fake columns
  cols_add <- as.character(2020:2039)
  
  DT[, (cols_add) := 0]
  
  for (col in cols_add) {
    set(DT, i = 1L, j = col, value = state[1, total] * abs(rnorm(1, mean = 10)) + state[1, total])
    set(DT, i = 2L, j = col, value = state[2, total] * abs(rnorm(1)) + state[2, total])
    set(DT, i = 3L, j = col, value = state[3, total] * abs(rnorm(1)) + state[3, total])
    set(DT, i = 4L, j = col, value = state[4, total] * abs(rnorm(1, mean = 10)) + state[4, total])
  }

  DT <- 
    DT %>% 
    tidyr::pivot_longer(cols = as.character(2020:2039))