Table extraction using rvest from a website with selection

I am trying to get a table from this page here: http://ift.tt/2p2W45o However, I will have to select a type of instruments before I go further. I would like to select the following two: "National Bank of the Republic of Kazakhstan" and "Ministry of Finance of the Republic of Kazakhstan".

I have tried the following code:

library(rvest)
p <- url %>%
read_html() %>%
html_nodes(xpath='//*[@id="pl1_11"]/table') %>%
html_table()

and I am getting:

list()

Any suggestions?