library(scales)
library(ggplot2)
library(lubridate)
DT <- data.table(yyyymm = ym(c("202207", "202307")), power = c(570.37, 559.39))
ggplot(DT, aes(x = yyyymm, y = power, fill = yyyymm)) +
  geom_bar(position = "stack", stat = "identity")+
  scale_y_continuous(breaks = seq(400, 600, 50), limits = c(400, 600), oob = rescale_none) + 
  theme(legend.position = "none")