Database schema:

CREATE TABLE "Answer" (
	"AnswerText" TEXT -- example: ['44', '37'],
	"SurveyID" INTEGER -- example: ['2014', '2016'],
	"UserID" INTEGER -- example: ['2', '1'],
	"QuestionID" INTEGER -- example: ['2', '1'],
	PRIMARY KEY ("UserID", "QuestionID"), 
	CONSTRAINT fk_answer_question FOREIGN KEY("QuestionID") REFERENCES "Question" (questionid),
	CONSTRAINT fk_answer_survey FOREIGN KEY("SurveyID") REFERENCES "Survey" ("SurveyID")
)


CREATE TABLE "Question" (
	questiontext TEXT -- example: ['What is your age?', 'What is your gender?'],
	questionid INTEGER -- example: ['2', '1'],
	PRIMARY KEY (questionid)
)


CREATE TABLE "Survey" (
	"SurveyID" INTEGER -- example: ['2014', '2016'],
	"Description" TEXT -- example: ['mental health survey for 2014', 'mental health survey for 2016'],
	PRIMARY KEY ("SurveyID")
)

Question: How many users answered "Yes" to the question "Have you had a mental health disorder in the past?" in 3 consecutive years starting from 2016?
Evidence: question refers to questiontext; answered 'Yes' to question refers to AnswerText = 'Yes'; 3 consecutive years starting from 2016 refers to SurveyID = 2016 and SurveyID = 2017 and SurveyID = 2018

SQL:
SELECT COUNT(T2.UserID) FROM Question AS T1 INNER JOIN Answer AS T2 ON T1.questionid = T2.QuestionID WHERE T2.SurveyID IN (2016, 2017, 2018) AND T1.questiontext LIKE 'Have you had a mental health disorder in the past?' AND T2.AnswerText = 'Yes'