What is the least common faculty rank?
CREATE TABLE department (
    dno number,
    division text,
    dname text,
    room text,
    building text,
    dphone number
)

CREATE TABLE minor_in (
    stuid number,
    dno number
)

CREATE TABLE student (
    stuid number,
    lname text,
    fname text,
    age number,
    sex text,
    major number,
    advisor number,
    city_code text
)

CREATE TABLE gradeconversion (
    lettergrade text,
    gradepoint number
)

CREATE TABLE enrolled_in (
    stuid number,
    cid text,
    grade text
)

CREATE TABLE faculty (
    facid number,
    lname text,
    fname text,
    rank text,
    sex text,
    phone number,
    room text,
    building text
)

CREATE TABLE course (
    cid text,
    cname text,
    credits number,
    instructor number,
    days text,
    hours text,
    dno number
)

CREATE TABLE member_of (
    facid number,
    dno number,
    appt_type text
)
SELECT rank FROM faculty GROUP BY rank ORDER BY COUNT(*) LIMIT 1
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the least common faculty rank? ### Input: CREATE TABLE department (
    dno number,
    division text,
    dname text,
    room text,
    building text,
    dphone number
)

CREATE TABLE minor_in (
    stuid number,
    dno number
)

CREATE TABLE student (
    stuid number,
    lname text,
    fname text,
    age number,
    sex text,
    major number,
    advisor number,
    city_code text
)

CREATE TABLE gradeconversion (
    lettergrade text,
    gradepoint number
)

CREATE TABLE enrolled_in (
    stuid number,
    cid text,
    grade text
)

CREATE TABLE faculty (
    facid number,
    lname text,
    fname text,
    rank text,
    sex text,
    phone number,
    room text,
    building text
)

CREATE TABLE course (
    cid text,
    cname text,
    credits number,
    instructor number,
    days text,
    hours text,
    dno number
)

CREATE TABLE member_of (
    facid number,
    dno number,
    appt_type text
) ### Response: SELECT rank FROM faculty GROUP BY rank ORDER BY COUNT(*) LIMIT 1