Those statistics are over a decade old, they also clearly summarise the danger of 20mm sized batteries.
'RESULTS: All 3 data sets signal worsening outcomes, with a 6.7-fold increase in the percentage of button battery ingestions with major or fatal outcomes from 1985 to 2009 (National Poison Data System). Ingestions of 20- to 25-mm-diameter cells increased from 1% to 18% of ingested button batteries (1990–2008), paralleling the rise in lithium-cell ingestions (1.3% to 24%). Outcomes were significantly worse for large-diameter lithium cells (≥20 mm) and children who were younger than 4 years. The 20-mm lithium cell was implicated in most severe outcomes.'
