https://www.hrw.org/legacy/backgrounder/arms/cluster031803.htm

This a report from 2003 regarding all US cluster munitions. It's largely based on US Pentagon reports. The specific munitions the US is sending to Ukraine are the 155mm DPICM M483A1 & M864 artillery projectiles (2nd bullet point on the list). The 14% dud rate it reports is from a 2000 study, which admits the munitions are old which is what caused a higher-than-expected dud rate when used in the field.

So yes, assuming a linear half-life, the dud rate of these munitions is probably closer to 30% now (which, by the way, is the number the US uses to accuse Russia for its use of cluster munition and their high dud rate).