pacman::p_load(RISmed)
Span <- 2001:2017
Tally <- sapply(Span, 
                function(i) {
                  QueryCount(EUtilsSummary('deep learning',
                             type = 'esearch',db = 'pubmed',
                             mindate = i, maxdate = i))
                }
)
names(Tally) <- Span
barplot(Tally, las = 2, ylim = c(0, 1500), main = "", ylab = "Number of Articles")