library(ggplot2) # this allows the plot magic

# data retrieval
x <- c(1, 3, 6, 11, 12, 15, 19, 23, 28, 33, 35, 39, 47, 60, 66, 73)
y <- c(3180, 2960, 3220, 3270, 3350, 3410, 3700, 3830, 4090, 4310, 4360, 4520, 
       4650, 5310, 5490, 5540)
dayweight <- data.frame(x,y)
colnames(dayweight) <- c("Lebenstag", "Gewicht")
rm(x,y)

# do the plot
ggplot(dayweight, aes(x = Lebenstag, y = Gewicht)) +
  geom_point(colour="blue", size = 2.5) +  # Data as points
  geom_line(colour="blue", size = 0.8) +  # line to connect points
  # line model, no confidence intervall (level=0)
  geom_smooth(method = "lm", colour = "black", level = 0) +
  ggtitle("Gewicht des Babys") +  # plot titel
  ylab("Gewicht in Gramm") +  # label of y-axis
  # x-axis dividing all the 10 instead of all the 20 days
  scale_x_continuous(breaks = seq(0,70,by=10)) +
  # y-axis dividing all the 500 instead of all the 1000 gramms
  scale_y_continuous(breaks = seq(3000,5500,by=500))