What years are included in this data set? What are the dimensions of the data frame and what are the variable or column names?
(Using inline r code)
The years are 1940 to 2002.
The data set includes 63 rows and 3 columns.
The variable names are: year, boys, girls.

How do these counts compare to Arbuthnot’s? Are they on a similar scale?
Arbuthnot had 30% more variables. That is a similar scale.

Make a plot that displays the boy-to-girl ratio for every year in the data set. What do you see? Does Arbuthnot’s observation about boys being born in greater proportion than girls hold up in the U.S.? Include the plot in your response.

## 
## Call:
## lm(formula = present$ratio ~ present$YearShifted)
## 
## Residuals:
##        Min         1Q     Median         3Q        Max 
## -0.0049082 -0.0015177  0.0002256  0.0013777  0.0046923 
## 
## Coefficients:
##                       Estimate Std. Error  t value Pr(>|t|)    
## (Intercept)          1.0547491  0.0005338 1976.105  < 2e-16 ***
## present$YearShifted -0.0001061  0.0000145   -7.318 6.58e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.002093 on 61 degrees of freedom
## Multiple R-squared:  0.4675, Adjusted R-squared:  0.4588 
## F-statistic: 53.55 on 1 and 61 DF,  p-value: 6.58e-10

The model does appear to show that boys are being born at a higher rate, but it appears that that difference is shrinking slowly.
A linear model comparing year to the ratio is significant at the .001 level. The ratio is very slowly getting closer to parity.

In what year did we see the most total number of births in the U.S.?
The most total live births occurred in 1961, during which 4268326 children were born.

present[[which.max(present$boys+present$girls),1]]
## [1] 1961
head(present)
##   year    boys   girls    ratio YearShifted
## 1 1940 1211684 1148715 1.054817           1
## 2 1941 1289734 1223693 1.053969           2
## 3 1942 1444365 1364631 1.058429           3
## 4 1943 1508959 1427901 1.056767           4
## 5 1944 1435301 1359499 1.055757           5
## 6 1945 1404587 1330869 1.055391           6
summary(present)
##       year           boys             girls             ratio      
##  Min.   :1940   Min.   :1211684   Min.   :1148715   Min.   :1.046  
##  1st Qu.:1956   1st Qu.:1799857   1st Qu.:1711405   1st Qu.:1.050  
##  Median :1971   Median :1924868   Median :1831679   Median :1.051  
##  Mean   :1971   Mean   :1885600   Mean   :1793915   Mean   :1.051  
##  3rd Qu.:1986   3rd Qu.:2058524   3rd Qu.:1965538   3rd Qu.:1.053  
##  Max.   :2002   Max.   :2186274   Max.   :2082052   Max.   :1.059  
##   YearShifted  
##  Min.   : 1.0  
##  1st Qu.:16.5  
##  Median :32.0  
##  Mean   :32.0  
##  3rd Qu.:47.5  
##  Max.   :63.0
dim(present)
## [1] 63  5