Don't know if this is the right way to read these but here gos.

.....Southern Oscillation Index

In 1889 it read in March -27.5
In 1896 it read in May -42.2.
In 1997 it read in May -22.4.
in 2015 it read in July -14.7.

So it I have read it right its along way to go to get a record which it may do.

 http://www.bom.gov.au/climate/current/soihtm1.shtml