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: Among respondents who participated in the survey in 2016, what percentage had a mental health disorder in the past?
Evidence: respondents and 'users' are synonyms; percentage = divide(count(SurveyID = 2016& QuestionID = 32 & AnswerText = 'Yes'), count(SurveyID = 2016& QuestionID = 32))*100%

SQL:
SELECT CAST(SUM(CASE  WHEN T1.AnswerText LIKE 'Yes' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.SurveyID) FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T1.QuestionID = 32 AND T1.SurveyID = 2016