Watch Tower Pennsylvania's form 990-T for the year ending 31 Aug 2017 has become available here: https://apps.irs.gov/pub/epostcard/cor/111857820_201708_990T_2018091015669414.pdf
Surprisingly, book value of its assets has almost doubled from $558.8M to $1,004.2M.
So, book value of assets of WTS Pennsylvania was $965.8M in 2011, $1,119.1 M in 2012, $1,154.5M in 2013, $1,020.4M in 2014, $593.75M in 2015, $558.8M in 2016, and $1,004.2M in 2017.
Book value of assets of WTS NY was $399.3M in 2009, $675.4M in 2014, $1,451.2M in 2016, and $1,590.2M in 2017.
Combined book value of the two societies' assets was $1.7 billion in 2014, $2 billion in 2016, and $2.6 billion in 2017.
The returns are available here: https://drive.google.com/drive/folders/1_I8jBbaSStIp4-1a0FODN2h4I6fpltBs?usp=sharing
Surely, book value of assets doesn't completely accurately reflect the org's financial situation. But this is still a good indicator, and it would be interesting to read what do proponents of the "WTS hides assets from lawsuits" theory think about the above-mentioned numbers.