Translate the following question to SQL: What is the total access count of documents that are of the most common document type?

Schema: CREATE TABLE Roles (
    role_code VARCHAR(15)   PRIMARY KEY,
    role_description VARCHAR(80),
    UNIQUE (role_code)
);

CREATE TABLE Users (
    user_id INTEGER   PRIMARY KEY,
    role_code VARCHAR(15) NOT NULL,
    user_name VARCHAR(40),
    user_login VARCHAR(40),
    password VARCHAR(40),
    FOREIGN KEY (role_code) REFERENCES Roles(role_code)
);

CREATE TABLE Document_Structures (
    document_structure_code VARCHAR(15)   PRIMARY KEY,
    parent_document_structure_code VARCHAR(15),
    document_structure_description VARCHAR(80),
    UNIQUE (document_structure_code)
);

CREATE TABLE Functional_Areas (
    functional_area_code VARCHAR(15)   PRIMARY KEY,
    parent_functional_area_code VARCHAR(15),
    functional_area_description VARCHAR(80) NOT NULL,
    UNIQUE (functional_area_code)
);

CREATE TABLE Images (
    image_id INTEGER   PRIMARY KEY,
    image_alt_text VARCHAR(80),
    image_name VARCHAR(40),
    image_url VARCHAR(255)
);

CREATE TABLE Documents (
    document_code VARCHAR(15)   PRIMARY KEY,
    document_structure_code VARCHAR(15) NOT NULL,
    document_type_code VARCHAR(15) NOT NULL,
    access_count INTEGER,
    document_name VARCHAR(80),
    UNIQUE (document_code),
    FOREIGN KEY (document_structure_code) REFERENCES Document_Structures(document_structure_code)
);

CREATE TABLE Document_Functional_Areas (
    document_code VARCHAR(15) NOT NULL,
    functional_area_code VARCHAR(15) NOT NULL,
    FOREIGN KEY (functional_area_code) REFERENCES Functional_Areas(functional_area_code),
    FOREIGN KEY (document_code) REFERENCES Documents(document_code)
);

CREATE TABLE Document_Sections (
    section_id INTEGER   PRIMARY KEY,
    document_code VARCHAR(15) NOT NULL,
    section_sequence INTEGER,
    section_code VARCHAR(20),
    section_title VARCHAR(80),
    FOREIGN KEY (document_code) REFERENCES Documents(document_code)
);

CREATE TABLE Document_Sections_Images (
    section_id INTEGER NOT NULL  PRIMARY KEY,
    image_id INTEGER NOT NULL  PRIMARY KEY,
    PRIMARY KEY (section_id, image_id),
    UNIQUE (section_id, image_id),
    FOREIGN KEY (image_id) REFERENCES Images(image_id),
    FOREIGN KEY (section_id) REFERENCES Document_Sections(section_id)
);
user
SELECT sum(access_count) FROM documents GROUP BY document_type_code ORDER BY count(*) DESC LIMIT 1
assistant