Problem with creating DataFrame using Dictionary

[ift38375]

I want to count particular column occurrence in Dataframe with given below Dataframe ?

import pandas as pd
diSales= { 2016:{'qtr1':34500,'qtr2':56000,'qtr3':47000,'qtr4':49000},
           2017:{'qtr1':44900,'qtr2':46100,'qtr3':57000,'qtr4':59000},
           2018:{'qtr1':54500,'qtr2':51000,'qtr3':57000,'qtr4':58500},
           2019:{'qtr1':61000}
         }
ks = pd.DataFrame(diSales)
ptr = ks.2016.count()
print(ptr)

but when i was trying then showing error " invalid syntax ?
is dataframe allow operation only on alphabetical column names instead of numeric column name ?