Add User Registration Date to User Profile

<?php
function add_registration_date($user) {
    $register_date = get_the_author_meta('user_registered', $user->ID);
    ?>
    <h3>Registration Date</h3>
    <table class="form-table">
        <tr>
            <th><label for="registration_date">Registered</label></th>
            <td>
                <input type="text" name="registration_date" id="registration_date" value="<?php echo esc_attr($register_date); ?>" class="regular-text" readonly />
            </td>
        </tr>
    </table>
    <?php
}
add_action('show_user_profile', 'add_registration_date');
add_action('edit_user_profile', 'add_registration_date');