Solve the following sql problem:
According to 2016's survey, what is the number of users with a mental health disorder in the past?

Schema:
SCHEMA:
- Table: Question
  - Column: questiontext
    - Samples: [What is your age?, What is your gender?, What country do you live in?, If you live in the United States, which state or territory do you live..., Are you self-employed? (truncated)]
  - Column: questionid
    - Samples: [1, 2, 3, 4, 5]
- Table: Survey
  - Column: SurveyID
    - Samples: [2014, 2016, 2017, 2018, 2019]
  - Column: Description
    - Samples: [mental health survey for 2014, mental health survey for 2016, mental health survey for 2017, mental health survey for 2018, mental health survey for 2019]
- Table: Answer
  - Column: AnswerText
    - Samples: [37, 44, 32, 31, 31]
  - Column: SurveyID
    - Samples: [2014, 2014, 2014, 2014, 2014]
  - Column: UserID
    - Samples: [1, 2, 3, 4, 5]
  - Column: QuestionID
    - Samples: [1, 1, 1, 1, 1]

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