The effect of the "stampless ballot" in WA State

The current WA State turnout percentage for Primary 2018 will be one of the highest for the 19 Primary elections since year 2000. The 1.7M votes will be the largest number of votes ever returned for a primary election in WA State. My initial inference is that the new stampless ballots are bringing an entire new voter pool into play. WA as a state is beset by both by rural poverty and independent voters. The nearest comparable Legislative District election year is a Presidential year (2016):

(Primary2018) - (Primary 2016)

1710872 - 1421841

[1] 289031

(Primary2018) / (Primary 2016)

1710872/1421841

[1] 1.203279

A twenty percent increase in votes for General Election 2018 because of stampless ballots means an entirely new voter profile for WA State.

10:04 AM 8/14/2018

http://results.vote.wa.gov/results/20180807/Turnout.html

County	Registered	Ballots	Turnout %	Updated	Next	Estimated
Total	4,299,119	1,710,872	39.80%	8/13/2018	8/14/2018	32,140
				5:34 PM	4:00 PM

https://www.sos.wa.gov/elections/research/voter-turnout-by-election.aspx :

# R 3.5 'data.table' code:

fread("WC_Historical_Election_Turnout.csv")[year(mdy(ElectionDate)) >= 2000 & !is.na(Turnout) & like(Description,"Primary"),][order(-Turnout)]

ElectionDate	Description	Counties	Precincts	Registered	Ballots	Turnout
9/14/2004	2004 Primary	NA	NA	3279205	1480247	45.14%
8/19/2008	Primary	39	6674	3417355	1455756	42.60%
8/17/2010	Primary	39	6778	3592079	1471791	40.97%
9/19/2000	2000 Primary	NA	NA	3234700	1319775	40.80%
9/19/2006	2006 Primary	NA	NA	3182209	1243992	39.09%
8/7/2012	Primary	39	6978	3731657	1435928	38.48%
8/2/2016	Primary	39	7147	4102624	1431058	34.88%
5/24/2016	Presidential Primary	39	7142	4088029	1421841	34.78%
9/17/2002	2002 Primary	NA	NA	3238601	1107861	34.21%
9/20/2005	2005 Primary	NA	NA	2701807	863489	31.96%
8/5/2014	Primary	39	6978	3925663	1222710	31.15%
8/18/2009	Primary	32	4785	2334067	724598	31.04%
8/16/2011	Primary	35	5123	2776149	819991	29.54%
8/21/2007	2007 Primary	NA	NA	2680339	757311	28.25%
8/1/2017	Primary	35	6351	3781977	1017946	26.92%
8/6/2013	Primary	36	3505	3221285	837098	25.99%
8/4/2015	Primary	34	5917	3356735	817876	24.37%
9/18/2001	2001 Primary	NA	NA	323927	62657	19.34%
9/16/2003	2003 Primary	NA	NA	1076966	194001	18.01%